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*For correspondence. (e-mail: nkgarg123@yahoo.com)

Alarming scarcity of water in India N. K. Garg1,* and Q. Hassan2 1Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi 110 016, India 2Department of Civil Engineering, Jamia Millia Islamia, New Delhi 110 025, India

In this article the assessment of utilizable water resources of India, based on various studies by the government, has been reviewed and analysed. The analysis yields that the utilizable water resources are overestimated in various studies, ranging from 66% to 88%. We have estimated the utilizable water resources as 668 billion cubic metre (BCM) against 1110 BCM of CWC, 1209 to 1255 BCM of NCIWRDP and 1122 BCM of the National Water Policy of India. The consequence will be alarming as the projected demand of even 897 BCM, corresponding to low demand scenario, cannot be met even after full development of utilizable water resources. The analysis also revealed that almost all the basins would become water-deficit, and raises a big question about the availability of water through inter-basin transfer. It is also shown that the ground-water has already been overexploited as far back as 1997–98. Therefore, contrary to the previous studies like those of NCIWRDP, CWC, etc., water scarcity is alarming and calls for urgent action before it becomes unmanageable.

Keywords: Assessment, management, utilizable water resources, water availability and scarcity. INDIA is facing a serious problem of natural resource scarcity, especially that of water in view of population growth and economic development. Water being a prime natural resource, a basic human need and a precious natio-nal asset, its use needs appropriate planning, development and management. But surprisingly, the recent report of the National Commission for Integrated Water Resources Development Plan (NCIWRDP)1, states: ‘Taking into ac-count the water availability and the requirements till the year 2050, the Commission concludes that there is no need to take an alarmist view’. This made us suspect the findings of the Commission, as there is all-round problem of water scarcity, groundwater depletion, etc. This moti-vated us to investigate whether there are any misfindings in the estimates of utilizable water resources. Since water resources data are classified, and even a recent article2 on water resources of India has not given any new estimates of utilizable water resources but only replicated the tables or figures of NCIWRDP, Central Water Commission (CWC)3, etc., the previous original studies carried out by various government organizations

and commissions, running into several volumes, were stud-ied and analysed. The analysis revealed that the utilizable water resources of India are much lower and are overes-timated in various studies ranging from 66% to 88%. Water scarcity will be alarming as the projected demand1 of even 897 billion cubic metre (BCM), corresponding to low demand scenario, cannot be met even after full deve-lopment of the water resources. After analysing the previ-ous studies, we have also provided new estimates of utilizable water resources for each river basin. We have also identified the basins as water-deficit or surplus de-pending upon their water requirements and utilizable water resources. It is also shown that the groundwater is already being overexploited since 1997–98.

Utilizable surface water

The average annual virgin (natural) flow at the terminal point of a river is generally reckoned as the water re-sources potential of the river basin4. The assessment of water resources of India from various studies1,3–7 ranges between 1673 and 1953 BCM. The latest estimate of total water resources of India as assessed by NCIWRDP is 1952.87 BCM, but this cannot be fully put to beneficial use because of topographical and other constraints. Utilization1 of water resources can be taken as the quan-tum of withdrawable water from its place of natural oc-currence, such as river or groundwater. Withdrawablity of water largely depends on the existence/possibility of stor-age and diversion structures and land availability. About 80–90% of the river flows occur during four months of the monsoon season. For the use of water dur-ing the non-monsoon seasons, there is a need to create storage capacities in reservoirs and tanks. The total stor-age built up in the projects completed up to 1995 is about 174 BCM. From projects under construction, another 76 BCM of storage capacity is likely to be added. From identified future projects another 132 BCM can be added, making a total of 382 BCM. An additional live storage capacity of 3 BCM is estimated to be created through me-dium projects1. All these aggregate to a total of 385 BCM. The NCIWRDP also states that the CWC has estimated the utilizable surface water in each river basin consider-ing suitable sites/locations for diversion and for storage structures. The CWC has estimated the utilizable water in each river basin from surface structures as 690.31 BCM (Table 1). NCIWRDP and the National Water Policy8 have

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also adopted the utilizable surface flow as 690.31 BCM, as estimated by CWC. Utilizable surface water resources have been estimated in the past also. The Irrigation Commission5 summed up the country’s utilizable surface water resources as 666 BCM. Rao6 suggested that the quantum should be 50% of the country’s available annual run-off (1645 BCM). The Natio-nal Commission on Agriculture (NCA)7 estimated the uti-lizable quantity from surface water to be 700 BCM.

Groundwater resources

Groundwater is an annually replenishable resource and its availability is non-uniform in space and time. A complexity of factors – hydrogeological, hydrological and climatolo-gical – control groundwater occurrence and movement. Only freshwater was included and saline areas were not included in the assessment of groundwater resources in various studies. Further, annually replenishable compo-nent of groundwater was considered for use in develop-mental planning. The replenishable groundwater resource was essentially a dynamic one, which is replenished an-nually or periodically by rainfall, irrigation return flow, canal seepage, tank seepage, etc.

Dynamic groundwater or replenishable groundwater

The Irrigation Commission reported that no systematic quantitative assessment of groundwater has been made

so far5. However, a rough assessment of groundwater resources has been attempted by Raghava Rao5. The Irri-gation Commission report summed up in the end: ‘the draft, at present, on account of domestic and industrial uses is estimated to be of the order of 65 BCM. The groundwater resources available for irrigation and future draft for domestic and industrial wells, may be of the order of 204 BCM’. The NCA in its report7 assessed the total groundwater resource of India as 670 BCM, of which 450 BCM gets regenerated during the non-monsoon period as surface water. This 670 BCM included 500 BCM as natural re-charge from precipitation. On full development of water resources the groundwater is estimated to increase to 850 BCM, of which 450 BCM is again assumed to be available as regenerated surface water. The utilizable ground-water extraction was assessed as 350 BCM. The CWC3 adopted the possible utilization from ground-water as 418.54 BCM, which was taken from the estimates of CGWB (see Table 1). Based on a large amount of data with detailed analysis, the CGWB in 1994–95 estimated9 the replenishable ground-water as 431.9 BCM. The CGWB also mentions results of previous studies, including those of the NCA7 in its re-port. The figure of 431.9 BCM is taken as the sum of the recharge of 342.4 BCM from rainfall and the additional recharge of 89.5 BCM from the canal irrigation system. A minimum provision of 15% of total groundwater re-sources was kept for domestic, industrial and other uses. The remaining 85% can be made available for irrigation,

Table 1. Basin-wise annual utilizable water resources3

Estimated utilizable flow, Utilizable groundwater excluding groundwater (CGWB assessment 1983–84) Total utilizable flow Basin (BCM) (BCM) (BCM)

Indus (up to border) 46.000 17.810 63.810 Ganga 250.000 172.010 422.010 Brahmaputra 24.000 20.820 46.15 Barak 1.330 Godavari 76.300 44.980 121.280 Krishna 58.000 24.620 82.620 Cauvery 19.000 10.420 29.420 Pennar 6.858 5.350 12.208 East-flowing rivers between Mahanadi and Pennar 13.110 11.690 24.800 East-flowing rivers between Pennar and Kanyakumari 16.732 21.080 37.812 Mahanadi 49.990 18.200 68.190 Brahmani and Baitarni 18.297 7.890 26.187 Subarnarekha 6.813 2.850 9.663 Sabarmati 1.925 4.380 6.305 Mahi 3.095 4.440 7.535 West-flowing rivers of Kutch Saurashtra, including Luni 14.980 12.610 27.590 Narmada 34.500 13.000 47.500 Tapi 14.500 6.730 21.230 West-flowing rivers from Tapi to Tadri, including Tadri 11.936 8.980 20.916 West-flowing rivers from Tadri to Kanyakumari 24.273 7.740 32.013 Area of inland drainage in Rajasthan desert – 1.330 1.330 Minor river basins draining to Bangladesh and Burma – 0.280 0.280

Total 690.309 418.540 1108.849 say 690 say 1110

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but only 90% of it has been taken as utilizable groundwater resources for irrigation9, leaving 10% to maintain river ecology. This amounts to around 91.5% of the total ground-water resources as utilizable. Accordingly, the utilizable groundwater resources can be taken as 313.3 BCM (0.915 × 342.4) from natural recharge and 81.9 BCM (0.915 × 89.5) from recharge due to canal irrigation system9, making the total utilizable groundwater resources to be about 395.2 BCM. The NCIWRDP1 has also adopted the replenishable groundwater resources as 431.9 BCM as given in CGWB report9 and the total utilizable groundwater resources as 396 BCM.

Water resources at a glance

It is observed that most of the studies estimate the water resources of India as 1880 BCM, while the total utilizable water resources vary considerably. The NCA has esti-mated7 the total utilization as 1050 BCM. The total utiliz-able water resources of India, according to the CWC3 are 1110 BCM (Table 1), while NCIWRDP1 estimated the same as 1086 BCM plus additional return flows (123 BCM for low-demand scenario or 169 BCM for high-demand sce-nario). Thus the total utilizable water resources of 1086 BCM would be further enhanced to 1209 or 1255 BCM, de-pending upon low- or high-demand scenario, according to NCIWRDP1.

Utilizable water resources – analysis

For the first time, the Irrigation Commission5 has broadly summed up the utilizable surface water resources of the country as 666 BCM5. The Commission5 also observed that ‘surface and groundwater resources’ are interlinked. Therefore, integrated studies are needed to cover both the resources’5, but no efforts were made by the Commission in this direction. Rao6 suggested that the quantum of uti-lizable water resources of India should be 50% of the available run-off.6 In our opinion, among all the Commissions, it was only the NCA7 that approached the problem of finding out the utilizable flows after taking into account the interactions between the ground- and surface water. Within the limita-tions of the available data, the NCA7, through detailed water-balance studies, has estimated that the utilizable surface flows aggregate to 700 BCM and groundwater to about 350 BCM, after full development of water re-sources. Of the total utilization of 700 BCM from surface water, 250 BCM was estimated through the storages hav-ing total live storage capacity of 350 BCM, with the es-timated evaporation losses from various storages as 100 BCM. The non-monsoon utilization of surface flows was expected to be 450 BCM as a result of the groundwa-ter natural recharge, regenerating itself as surface water. The extraction from groundwater, called as utilizable

groundwater, was estimated as 350 BCM, which would be available after full water-resources development. Thus according to NCA7, the utilizable water-resources from surface flows aggregate to the 700 BCM and from groundwater to about 350 BCM, making the total utiliz-able water resources to be 1050 BCM. Regeneration from groundwater to river, in the form of surface water, was considered as a part of utilizable flows from the surface water, besides the reservoir storage. The NCA has assumed the recharge from the natural precipi-tation as regenerated groundwater flow into the rivers and estimated it to be 450 BCM in the absence of any detailed study. Therefore, it may be concluded that the total utiliz-able surface water resources, according to the NCA, ag-gregated to about 700 BCM [250 BCM (storage–reservoir losses) plus 450 BCM regenerated groundwater flow into the rivers]. The details of utilizable flows7 are given in Table 2. The additional 350 BCM from groundwater was estimated to be available due to irrigation recharge after full water-resources development. The CWC3 reassessed the total utilizable water re-sources of the country as 1108.849 BCM; 690.309 BCM from surface structures plus 418.54 BCM from groundwater (Table 1). However, no details are given about the 690 BCM of utilizable surface water by CWC, but it is mentioned in the report that the NCA report7 is one of the sources in preparing estimates of basin-wise annual utili-zable water resources. According to the storage estimates available at that time, the CWC3 had considered the ex-pected total live storage capacity as 334 BCM, but no figure was given for reservoir losses. In order to find out a reasonable explanation for the 690 BCM, we investigated and analysed the previous studies, including those of the NCA. After the analysis it was found that the CWC had directly adopted the figures of utilizable surface water from the NCA report7. The total live storage capacity as considered by the NCA was 350 BCM, and it was reduced by 100 BCM to account for reservoir losses. Following the NCA report7, the reservoir losses corresponding to 334 BCM can be estimated to be 95 BCM. It would give utilizable water from reservoirs as

Table 2. Basin-wise annual utilizable flow7

River Utilizable flow* (BCM)

Indus basin 46 Ganga basin 250 Brahmaputra basin, including Barak 24 Mahanadi and other east-flowing rivers up to 91 Godavari Godavari, Krishna, and other east-flowing 190 southern rivers West-flowing rivers south of Tapi 30 Narmada and Tapi 49 West-flowing rivers north of Narmada 20

Total 700

*Excluding evaporation losses from reservoirs.

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Table 3. Comparison of utilizable flows of identical basins

Utilizable flow7 Estimated utilizable flow, Basin (BCM) excluding groundwater3 (BCM)

Indus basin 46 46 Ganga basin 250 250 Brahmaputra basin, including Barak 24 24 Godavari, Krishna and other east-flowing 190 190 southern rivers Godavari, Krishna, Cauvery, Pennar, east-flowing (76.3 + 58.0 + 19.0 + rivers between Mahanadi and Pennar, and 6.858 + 13.11 + 16.732) east-flowing rivers between Pennar and Kanyakumari Narmada and Tapi 49 49 (34.5 + 14.5)

239 (say 240) BCM. The reduction in utilizable water, due to the difference in live storage corresponding to the NCA and CWC estimates7,3, can be estimated as 10 BCM (250–240). Therefore, it reduces the figure of 700 BCM of utiliz-able flow of NCA estimate7 to 690 BCM of the CWC report3. The utilizable flows of identical river basins (high-lighted in Tables 1 and 2) as estimated by the CWC and NCA are compared in Table 3. It is evident from Table 3 that the CWC had directly adopted the values of the NCA. As already discussed, the estimates of utilizable flows of the NCA also included the interaction of surface and groundwater in the form of regenerated groundwater flows of 450 BCM into the rivers. These flows were taken as the natural groundwater recharge due to precipi-tation by the NCA. It is clear from Table 1 that the CWC had ignored this fact that estimated utilizable flows were taken after excluding the groundwater. The CWC added 418.54 BCM as utilizable groundwater to the estimated utilizable flows and estimated total utilizable flows as 1110 BCM. A combined figure of 418.54 BCM was taken as utiliz-able groundwater by the CWC without giving the break-up of natural recharge from rainfall and additional recharge due to the irrigation system. If the entire utilizable ground-water of 418.54 BCM was to be added to the utilizable surface flows, then the latter should have been reduced by 450 BCM by the CWC. Therefore, the total utilizable flows should have been estimated as 658.54 BCM (690 – 450 + 418.54) in place of adding 418.54 to 690 BCM. Hence, it is clear that the CWC has overestimated the total utilizable flows to a total of 1110 BCM, which should have been reduced to 658.54 BCM. Since then, subsequent reports of the CWC or NCIWRDP have taken the values from the CWC report3, and there-fore adopted the over-estimated figures of utilizable flows. The report of the National Water Policy of India has also adopted the over-estimated figure of 1122 BCM as total utilizable water resources.

Water requirement

Efforts have been made to estimate the water use and likely water requirements in the future by various investi-

gators1,3,6,7. Recent projections of water requirements made by the NCIWRDP are based on detailed studies. The water use in 1997 and water requirements in the future till the year 2050 have been worked out by the NCWIRDP. Water use in 1997–98 was estimated as 629 BCM, and projected water requirements in 2010, 2025 and 2050 were estimated as 694, 784, 973 BCM under low-demand, and 710, 843, 1180 BCM under high-demand scenarios respectively. These estimated water requirements also in-cluded evaporation losses. As discussed earlier, the uti-lizable water resources have been estimated after deducting evaporation losses7. Therefore, the corrected water use in 1997 was 593 BCM, and projected water requirements in 2010, 2025 and 2050 have been estimated as 652, 734, 897 BCM under low-demand, and 668, 793 and 1104 BCM under high-demand scenario respectively, after deducting the evaporation losses. It may be noted that the NCIWRDP has already taken into account the increased efficiencies, yields, etc. while estimating the water requirements. It is obvious that the total water requirement of 897 BCM, corresponding to low-demand scenario cannot be met even after full development of the utilizable water resources, as the corrected utilizable water resources corre-sponding to the CWC have been modified to 658.54 BCM. We have also worked out the total utilizable flows, basin-wise. In order to calculate the return flows, the basin-wise total water requirements were taken from the NCIWRDP report1. However, the report gave only basin-wise irrigation water requirements and the break-up for other uses in the basin was assumed proportionally, as shown in Table 4. We have estimated the total utilizable flows from surface and groundwater, and identified the water deficit and sur-plus basins.

Estimate of utilizable water resources

Based on the above analysis, it is fairly appropriate to assume that the utilizable water resources can be taken as the sum of the storages (excluding reservoir losses), and as dis-cussed earlier, 91.5% of total replenishable groundwater resources consisting of the natural groundwater recharge and total return flows to groundwater. In addition, return flows to the surface water were also added in the utiliz-able water resources.

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In order to calculate the return flows, it is reasonable to assume the achievable efficiencies according to the NCIWRDP report1, based on practical experience. Accordingly, the overall irrigation efficiencies were as-sumed1 as 60% from surface water and 75% from ground-water by the year 2050. Total return flows were taken as 24% from surface water and 15% from groundwater of the percentage of gross irrigation requirement (GIR). The projected national average values of GIR (or delta)1 in 2050 were 0.61 m from surface water and 0.49 m from groundwater. Around 90% of return flows from irrigation are expected to contribute to groundwater source and bal-ance 10% to surface water source. Return flows from domestic uses were assumed as 50% of supplies, out of which 85% would go to surface water and balance 15% to groundwater1. Return flows from industrial uses were esti-mated at an overall average of 50% of the supplies, all of which would go to the surface water. The priorities of water uses were in accordance with those of the National Water Policy of India8, starting from drinking, irrigation, hydropower, ecology, industries, navigation and other uses, depending upon the water availability. In view of this, the uti-lizable water resources were estimated by us as given below. The total possible live storage capacity has been worked out as 385 BCM by the CWC10, which was also adopted by the NCIWRDP1. The estimate of 385 BCM of live storage capacity was taken in the present study as the ultimate live storage capacity by 2050. We have some reservations about the feasibility of creating this quantity of live storage capacity and it will also be reduced due to sedimentation. Reservoir losses were taken on an average to be about 20% of live storages based on the CWC report4, reducing the useful live storage capacity to 308 BCM. The utilizable natural recharge was taken as 312.9 BCM (91.5% of 342 BCM). Therefore, the utilizable water flows of India were esti-mated as 621 BCM (308 + 313) without considering return flows. In addition, 91.5% of recharges due to irrigation system and return flows from other withdrawals were also considered as additional utilizable groundwater. The return flows to surface water were considered as additional utilizable surface water. Our basin-wise estimates of the utilizable water flows are given in Table 4. The total water use/required for all the uses in 2050 corresponding to low-demand scenario1 were considered in Table 4, while allocating the water for different uses according to priori-ties8 and correspondingly the return flows were also cal-culated. The calculations made in Table 4, in order to estimate the utilizable flows, are self-explanatory. Basin-wise total utilizable surface water and ground-water, including return flows are given in columns 37 and 38 respectively (of Table 4). It may be noted that the summation of column 39 gives the total utilizable water as about 752 BCM, while the deficits/surpluses of column 40 add to around –145 BCM. However, it will give a false impression since the surplus utilizable water of one basin

is not available to another basin at present. Therefore, the total utilizable water is reduced from 752 to 668 BCM (Table 4) and net utilizable water basin-wise is given in column 41. Net utilizable water for a basin is taken as total utilizable water (column 39) if the basin is water-deficit; otherwise it is taken as total water requirement of the basin (column 8). Therefore, the total water deficit would be increased from 145 to 229 BCM. The deficits would further worsen, if the assumed efficiencies and yields are not achieved in practice. The water requirements1 and utilizable water resources are also compared basin-wise in Table 4. A basin is identi-fied as water-surplus (+) basin if the total utilizable water resources, including return flows in the basin are more than the water requirements, else it is identified as water-deficit (–). Table 4 shows that most of the basins are water-deficit, even if low-demand scenario is considered by 2050. It would also raise a big question on the possible availability of utilizable water of the order of 200–250 BCM, as considered by the NCIWRDP through inter basin transfer schemes. The scenario becomes worse if high water demands are considered for the analysis. Fol-lowing similar calculations as done for the low-demand scenario, the total deficit increases to 396 BCM for high-demand scenario. The utilizable water resources of 668 BCM, as esti-mated by us, were compared with the estimates of CWC3 and NCIWRDP1. The CWC estimate3 is 1110 BCM and that of NCIWRDP1 ranges from 1209 to 1255 BCM. Thus, these are overestimated compared to our estimate of uti-lizable water resources by 66–88%. All these estimates are based on the conventional water resources development. It is clear that the total water requirement of even 897 BCM in 2050, corresponding to low-demand scenario cannot be met even after full development of the utilizable water re-sources, which we estimate as 668 BCM. In fact, the im-pact of water scarcity in India can also easily be felt at present, as interstate water disputes are already worsening and causing social and political problems. This is in con-tradiction to the recommendations of the NCIWRDP1. It may be noted that the planning, development and management of water resources of India is based on the utilizable water resources of 1122 BCM, according to the National Water Policy of India8, while we estimate the utilizable water resources as 668 BCM. In absolute terms, the overestimation in the utilizable water resources is of the order of 454 BCM (1122–668) or about 1.68 times of 668 BCM. This requires an urgent attention of the policy makers and also to evolve a mechanism for the monitor-ing and implementation of the policies.

Groundwater development – already overexploited

According to the CGWB9, groundwater development was of the order of 31.92% in 1995, and it suggested a huge

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scope for additional groundwater development of the order of 70%. However, we have found that the groundwater was already overexploited by 1997 based on the analysis of the data of the NCIWRDP1. The groundwater withdrawals were estimated as 230 BCM in 1997 by the NCIWRDP1. As already discussed, live storage capacity from completed projects was about 177 BCM in 1995 and it was assumed to be fully utilized by the year 1997. Considering reservoir losses at 20%, the water withdrawal from storages would have been about 142 BCM. Since the total water uses in 1997–98 were 593 BCM after correction for evaporation losses1, the re-maining 451 (593–142) BCM would have come from groundwater, either in the form of direct pumping or through river diversions. The replenishable groundwater resource due to natural recharge was 342 BCM and recharge to groundwater due to generated return flow in 1997–98 was estimated1 as 143 BCM. Thus the total replenishable ground-water resource can be estimated as 485 BCM in 1997. The utilizable water resource from groundwater would be limited to 444 BCM (@ 0.915 of 485), while in fact 451 BCM of groundwater was used, after considering its in-teractions with surface water. This clearly shows over-exploitation of groundwater even in 1997–98. This is in contrast to the CGWB assessment9 that groundwater de-velopment was of the order of 32%; it suggested a huge scope for additional groundwater development. An urgent shift in the groundwater policy is called for to augment it through artificial recharge, rather than the existing policy of further development of groundwater. Otherwise, no water would be left for river diversions during the non-monsoon period.

Conclusion

This article is a review and analysis of various studies on utilizable water flows from surface and groundwater, and thereby the total utilizable water resources of India. The main findings can be summarized as follows. (i) The utilizable water resources of India are overesti-

mated in various studies ranging from 66% to 88%. (ii) The total utilizable water flows of India are estimated

as 668 BCM by us, as against 1110 BCM by the CWC3, 1209–1255 BCM by the NCIWRDP1 and 1122 BCM according to the National Water Policy of India8.

(iii) We have also estimated the basin-wise utilizable water flows.

(iv) It is also shown that most of the basins are water-deficit even if low-demand scenario is considered by 2050. The total deficit of water in all the deficit basins has been calculated as 229 BCM.

(v) The scenario becomes worse if high water demands are considered for the analysis. Following similar

calculations as done for the low-demand scenario, the total deficit increases to 396 BCM for the high-demand scenario.

(vi) It has also been shown that the groundwater had been overexploited even in 1997–98. This necessitates an urgent shift in the existing groundwater policy from further exploitation to augmentation.

The National Water Policy of India8 has also adopted the overestimated figure of utilizable water resources, which needs to be corrected. It may be noted that the pro-jected water demand of 897 BCM cannot be met even after full development of the water resources aggregating to about 668 BCM. The analysis yields that almost all basins will become water-deficit and this raises the big question upon the availability of water through inter-basin transfers. Therefore, contrary to the views of the NCIWRDP1, water scarcity is alarming and there is every reason to be worried. It may also be noted that this article only focuses on the quantity of utilizable water, assuming that all the water, including the return flows is of acceptable quality. The situation may be much worse in view of the deterio-rating ground- and surface water quality. It calls for urgent action to review and implement water policies/ plans in a time-bound manner in the light of the alarming water scarcity, before it becomes unmanageable, and to complete all possible storage works on priority basis. A shift in the approach of balancing the supply and demand is also required. This may call for an integrated approach of water supply and demand management. Water supplies must also be augmented with traditional approaches of water conservation locally, in addition to big projects.

1. Integrated water resources development: A plan for action, Report of the National Commission for Integrated Water Resources Develop-ment Plan, Ministry of Water Resources, New Delhi, 1999.

2. Kumar, R., Singh, R. D. and Sharma, K. D., Water resources of India. Curr. Sci., 2005, 89, 794–811.

3. Water resources of India, Publication No. 30/88, Central Water Commission, New Delhi, 1988.

4. Reassessment of water resources potential of India, Central Water Commission, New Delhi, 1993.

5. Report of the Irrigation Commission 1972, Irrigation Commission, Ministry of Irrigation and Power, New Delhi, 1972.

6. Rao, K. L., India’s Water Wealth, Orient Longman Ltd, New Delhi, 1975.

7. Report of the National Commission on Agriculture 1976, National Commission on Agriculture, Ministry of Agriculture, New Delhi, 1976.

8. National water policy, Ministry of Water Resources, Government of India, New Delhi, 2002.

9. Ground water resources of India, Central Ground Water Board, Ministry of Water Resources, New Delhi, 1995.

10. Storage in river basin of India, Central Water Commission, Ministry of Water Resources, New Delhi, 1997.

Received 23 February 2007; revised accepted 22 August 2007